کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
10244719 47700 2005 10 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Sn-modified Ni catalysts for aqueous-phase reforming: Characterization and deactivation studies
موضوعات مرتبط
مهندسی و علوم پایه مهندسی شیمی کاتالیزور
پیش نمایش صفحه اول مقاله
Sn-modified Ni catalysts for aqueous-phase reforming: Characterization and deactivation studies
چکیده انگلیسی
The catalytic deactivation of R-NiSn catalysts was explored during hydrogen production by aqueous-phase reforming (APR) of ethylene glycol. X-ray photoelectron spectroscopy and CO and H2 adsorption microcalorimetry were combined with previous characterization to show that R-NiSn catalysts are composed of a Ni core surrounded by a Ni3Sn alloy after heat treatments above 533 K. Adsorption studies (CO, H2, and N2), XPS, X-ray diffraction, and thermogravimetric analysis show that R-Ni15Sn catalysts deactivate by interaction with water under APR reaction conditions, rather than coking or Ni(CO)4 formation. Over the first 48 h on stream, deactivation proceeds rapidly by the sintering of small Ni particles and by the formation of NiSn surface alloys with lower catalytic activity and higher selectivity for the production of hydrogen by APR of dilute feed solutions. After several days on stream, R-Ni15Sn catalysts deactivate at a slower rate because of oxidation and dissolution by water, leading to Ni effluent concentrations near 50 wppm after 240 h on stream. The first-order deactivation constant can be improved from kd=0.0020h−1 to less than 0.0001 h−1 between 140 and 240 h on stream with the use of rigorous heat treatments at 623 K in H2 to form resilient NiSn alloys prior to reaction and/or with the use of energy-efficient stoichiometric feeds (water/ethylene glycol = 2).
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Catalysis - Volume 231, Issue 1, 1 April 2005, Pages 67-76
نویسندگان
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